Spiral staircase arrangement

Abstract

A round or spiral staircase is formed from post pieces and treads with the treads each having a collar portion which cooperates with the post pieces to form a complete post. The collars are rotatable relative to the post portions to allow the treads to be aligned for transportation. The post portions and collars are clamped together by a longitudinal screw with end caps closing the end post portions. The upper end cap has an opening therein so that a pourable settable liquid reinforced with glass-fiber can be poured down the hole post with the treads arranged spirally to integrate the collars and post portions into a complete rigid post.

I claim: 
     
       1. A spiral staircase subassembly for erection into a spiral staircase comprising in assembled combination, a central post formed from a plurality of coiaxial, hollow, axially separated post portions, a plurality of treads supported on said post in axially aligned position, each tread being formed from wood and comprising a tread portion extending to one side of the post and a collar portion coaxial with and arranged end to end with a respective pair of adjacent post portions, each said collar portion and associated tread portion being arranged for free rotation of said collar portion relative to an adjacent post portion about the axis of the post so as to allow the treads to rotate from said axially aligned position to a position in which they are separated angularly to form the spiral staircase, a pair of end cap members each mounted at a respective end of the post, a rod extending longitudinally of said post inside said post portions and said collar portions and engaged with said end cap members to hold said post portions and collar portions in coaxial end to end relation forming said post, each of said tread portions having a first opening adjacent a front edge and a second opening adjacent a rear edge whereby each tread portion can be accurately located in said angularly separated position relative to an adjacent tread portion by a member extending from the first opening of said each tread portion to the second opening of said adjacent tread portion, and means for integrating the post portions and collar portions into an integral post supporting said treads, said integrating means including a hollow continuous channel extending longitudinally of said central post through each of said post portions and collar portions and opening means in an uppermost one of said end cap members arranged to receive a pourable, settable liquid material into and through said channel. 
     
     
       2. The invention according to claim 1 wherein said collar portions and said post portions include axially extending interlocking projection means to provide interconnection between each of said collar means and a respective adjacent one of said post portions. 
     
     
       3. The invention according to claim 1 wherein each of said tread portions includes spike means extending therefrom into said channel whereby to engage with said settable liquid. 
     
     
       4. The invention according to claim 1 wherein said tread portion is formed separately from said collar portion. 
     
     
       5. The invention according to claim 4 wherein said tread portion includes a tongue for projecting radially into said collar portion. 
     
     
       6. The invention according to claim 5 wherein said collar portion includes a slot extending from one axial end of said collar portion for receiving said tongue. 
     
     
       7. The invention according to claim 4 wherein each of said post portions includes axially projecting flange means spaced inwardly from an outer face of said post portion for projecting into and cooperating with a respective one of said collar portions. 
     
     
       8. The invention according to claim 7 wherein said axially projecting flange means are arranged to project into engagement with one face of said tread portion. 
     
     
       9. The invention according to claim 1 wherein said collar portion and tread portion are cut from an integral tread piece so as to define an opening through said tread for receiving said settable liquid material. 
     
     
       10. The invention according to claim 9 wherein said tread piece is formed from a laminate material, upper and lower layers of which are removed at said post portion to receive an axially extending face of said post portion. 
     
     
       11. The invention according to claim 10 wherein the post portions are formed from tubular plastics material.